Cisco Interview Question

How would you design a thread pool in Java? Why do you need threads? How do you detect stale db connections? Can you do code review of this class from my code? (Interviewer shared code) Design for several readers reading from queue and several writers writing into it Details on how a web-app is developed What happens end to end when user types a URL to view books on Amazon.com Singleton - how to write for delayed instantiation but also thread safety